Input/output (I/O) circuits are used for transferring signals into or out of an integrated circuit (IC) device. The signals are transferred using specific signal transmission protocols. These protocols are generally classified into two classes, which are either a single-ended protocol or a differential protocol.
A differential protocol is preferred when the signals that are being transmitted are sensitive to noise. A differential protocol helps to eliminate noise by using two signals that are complementary to each other. Some of the common differential transmission protocols are the low voltage differential signaling (LVDS) protocol and the low voltage positive emitter coupled logic (LVPECL) protocol.
An I/O buffer circuit, which usually forms part of the I/O circuit, is generally utilized for providing input impedances or output impedances. However, a pin capacitance on an I/O buffer circuit has become a crucial designing consideration as the industry moves towards high speed as well as low power I/O circuits.
differential I/O buffer circuit generally includes a large pin capacitance because of its large sized resistors and large sized transistor. The large pin capacitance has significantly affected advancement towards transferring high speed differential signals through the differential I/O buffer circuit.